The Internet of Things, or “IoT” for short, represents an evolution of computer networks that seeks to connect many everyday objects to the Internet. Notably, there has been a recent proliferation of “smart” devices that are Internet-capable such as thermostats, lighting, televisions, cameras, and the like. In many implementations, these devices may also communicate with one another. For example, an IoT motion sensor may communicate with one or more smart lightbulbs, to actuate the lighting in a room, when a person enters the room.
The recent Institute of Electrical and Electronics Engineers (IEEE) wireless standard 802.11ah introduced the concept of a Target Wake Time (TWT), to allow stations that occasionally need to transmit to sleep longer. At the same time, TWT allows a wireless access point to split a large population of IoT clients into groups that contend at different times, limiting the contention and collision risks to subsets of the client population for a given time period. The underlying idea of this mechanism was to divide a cell in quadrants where clients transmit in turns.
IEEE 802.11ax reuses the TWT concept. 802.11ax also introduces Orthogonal Frequency-Division Multiple Access (OFDMA) and Uplink-Multiple User, Multiple-Input, Multiple-Output (UL-MUMIMO) modes. These modes allow an access point to cause spatially diverse client stations (STAs) to send uplink traffic at the same time over different streams, in UL-MUMIMO mode, or by allowing the access point to schedule each STA to only use a subset of the uplink transmission frame, in OFDMA mode.